Production method of puffed food and puffed food dough

ABSTRACT

A puffed food dough and method for producing a puffed food product from the dough. The dough contains soybean protein, starch and dietary fiber in a ratio by weight of from 1:0.2 to 0.8:0.01 to 0.4, respectively, and from 0.5 to 5 parts by weight of a vegetable foaming agent and from 150 to 300 parts by weight of water per 100 parts by weight in total of the soybean protein, starch, and dietary fiber. The dough does not contain a chemical leavening agent or yeast.

TECHNICAL FIELD

The present invention relates to a method for producing puffed food anda puffed food dough. More particularly, the invention relates to amethod for producing puffed food characterized by a higher content ofsoybean protein and dietary fiber and a lower content of cholesterol anda dough used for such food.

BACKGROUND ART

Recently, to avoid various problems caused by eating too much animalfood, low-calorie foodstuffs have been drawing public attention ashealthy food. In addition, the relation between food and prevention ofdiseases has been clarified, and it is known, for example, that thosecontaining fibers and less fat help to reduce risks of cancer, and thosecontaining fibers and less cholesterol reduce risks of coronary heartdiseases. Thus, healthy food that helps to maintain and promote humanhealth attracts public attention, and such food that is rich in proteinand low in calories and contains dietary fibers and the like is studied,and sold in the market.

Although various healthy foods have been studied and commercialized asdescribed above, because the term, "healthy food", has not been clearlydefined, and has for different meanings, it has caused a problem thatmisunderstanding or confusion on the part of consumers In order to solvethe problem, the U.S. Food and Drug Administration (FDA) has establisheda guideline stating, if total fat, saturated fat, cholesterol and sodiumcontained in a serving size of a particular foodstuff are higher thanspecified levels, the foodstuff cannot be claimed as being a healthyfood. More specifically, a foodstuff of a meal type, for example, cannotbe claimed as being healthy food, if total fat of 26.0 g or more,saturated fat of 8.0 g or more, cholesterol of 120 mg or more and sodiumof 960 mg or more are contained in a serving size of the particularfoodstuff. In the case of packaged foodstuffs, a nutritionalspecification showing contents of ingredients must be provided as well.

Of the above-mentioned healthy foods, those using a soybean proteininstead of animal meat protein are very important to prevent intake ofexcessive fat and calories. Since a soybean protein is particularlyexcellent in the balance of essential amino acids, and very nutritious,a variety of foodstuffs rich in protein and low in calories with asoybean protein contained-as a protein source are studied. As a part ofsuch study, addition of a soybean protein to such puffed food as breadhas been also studied. In a puffed food like bread which is made fromsuch milled grains as wheat flour, starches and such expanding agent asyeast and baking powder, if a soybean protein is used entirely or partlyin place of such material as wheat flour, the puffed food obtained islow in loaf capacity and gives a tough touch, when it is eaten, so afoodstuff that sufficiently satisfies the human taste has never beenobtained. In order to solve the problem, the inventors proposed a methodof obtaining a bread-like puffed food that comprises a soybean protein,wheat flour and eggs, and that has a high content of soybean protein bypuffing a dough using an expanding agent (see Japan Laid-open Pat. No.144936/1989).

The puffed food produced by such method as disclosed in the laid-openpatent is high in loaf capacity, excellent in touch, flavor andnutritional balance, and is favorably accepted in Japan, United Statesand many other countries. However, has the problem that the puffed foodobtained in such manner contains much cholesterol, and fails to meet theabove-mentioned FDA specification, because eggs that are high incholesterol content are used as a foaming agent for improving the touchand the puffing effect. It is another problem that the food cannot beserved to those who are religiously prohibited from eating eggs.Additionally, use of chemical expanding agents has been a problem aswell.

In the light of such problems, it is an object of the invention toprovide a method for producing a food superior in flavor, touch andnutritional balance, low in cholesterol content, and containing asoybean protein and dietary fibers and a dough for such puffed food.

SUMMARY OF THE INVENTION

The method of producing puffed food according to the invention comprisesthe step of heating a dough containing a soybean protein, starch anddietary fiber at the ratio of 1:0.2 to 0.8:0.01 to 0.4 (by weight) witha vegetable foaming agent of 0.5 to 5 parts by weight and water of 150to 300 parts by weight added to a total of 100 parts by weight of thesoybean protein, starch and dietary fiber. According to the method, thepuffed food obtained containing a soybean protein is dietary fiber andlower in cholesterol content.

In addition, the invention provides a puffed food dough used forproducing the puffed food. The dough is a foamed material containing anumber of fine foams formed therein, and puffed food similar to breadand cookies can be produced by heating the dough so that the dough ispuffed by evaporation of water content, and the soybean protein isgelled.

DETAILED DESCRIPTION OF THE INVENTION

The invention is constituted as described above, and a separated soybeanprotein that has high protein content (generally 85 to 90% in proteincontent), and is superior in gelling property, whiteness, odorlessnessand other properties is the most preferable, although any soybeanprotein that is gelled by adding water and heating can be used. As agrain size of the separated soybean protein is unspecified, separatedsoybean proteins commercially available, for example, Fuji Pro R, K andV [tradenames, all manufactured by Fuji Oil Co., Ltd., Japan ] can beemployed.

As for starch, those containing starch as a main ingredient, forexample, corn starch, potato starch, sweet potato starch, wheat starchand modified starch can be used.

For dietary fiber, any eatable dietary fiber source, either soluble orinsoluble, may be employed, such as polydextrose (90% or more in contentof dietary fiber) and corn fiber [ex., Nisshoku Celfer (tradename) at85% in content of dietary fiber] that mainly consist of dietary fibersas well as such food materials containing dietary fibers as bran(approximately 10% in content of dietary fibers), raw bean-curd refuse(approximately 4% in content of dietary fibers) and powdered bean-curdrefuse (approximately 40% in content of dietary fibers). Usage of suchdietary fiber sources should be adjusted by calculating the content ofdietary fibers, so that the above-mentioned ratio is realized.

According to the invention, contents of the soybean protein, starch anddietary fiber are adjusted to generally provide the ratio of 1:0.2 to0.8:0.01 to 0.4 (ratio by weight, also applicable hereinafter unless itis differently specified), preferably 1:0.33 to 0.7 0.05 to 0.3. If thecontent of starch is higher than 0.8 in relation to 1 part of soybeanprotein, the puffing property is inferior, and it is difficult to obtaina puffed product having a high loaf capacity, while a nutrition balanceis poor, if the content is lower than 0.2. Similarly, if the content ofdietary fiber in relation to 1 part of the soybean protein exceeds 0.4,the puffing property is insufficient, the puffed food is rough to thetongue and difficult to swallow, while addition of dietary fibers ismeaningless, if the content is lower than 0.01.

According to the invention, a vegetable foaming agent is used instead ofegg-originated foaming agents. Thus, a puffed food containing lesscholesterol is obtained. Various foaming agents may be used as long asthey are vegetable, including such soybean protein foaming agent asenzyme-decomposed soybean proteins, cellulose foaming agents of finepowders [ex., Celcream [tradename], a creamy product containing 12.5% ofsolid ingredients (97.6% in content of cellulose in the solidingredients)] and freeze-dried yam powders. Specifically, soybeanprotein foaming agents are preferable because of their superior foamingproperty and high foam stability and thermal stability, and because theyof the invention meet the object of providing a high content of soybeanprotein. Such soybean protein foaming agents are available as Versa WhipK, Mirafoam K [tradenames, both of them manufactured by Stery, U.S.A.]and Fuji Soft [tradename, manufactured by Fuji Oil Co., Ltd., Japan]. Inthe case of using bean-curd refuse as a dietary fiber source, as thefoaming agent, it is preferable to use a cellulose foaming agent of finepowders only or together with other foaming agents, because it iseffective for giving a soft touch to the food, and reducing a touchcharacteristic of the bean-curd refuse.

The foaming agent is used at content of 0.5 to 5, preferably about 1 to2 parts by weight in relation to 100 parts by weight in total of thesoybean protein, starches and dietary fibers. If the content of foamingagent is lower than 0.5 parts by weight in relation to 100 parts byweight of a mixture of the above ingredients, it provides aninsufficient foaming performance, and puffing is insufficient, resultingin a food of low loaf capacity, while a content higher than 5 parts byweight is relatively unpreferable, because the food is puffed too much,and an excessive void parts are formed.

Incidentally, a foam stabilizing agent such as agar, vegetable gums(guar gum, psyllium seed gum, locust bean gum, etc.), water-solublestarches, water-soluble soybean protein, glucomannans, carboxymethylcellulose and chitosan can be also used in combination with theabove-mentioned foaming agents. Out of them, such viscous materials asvegetable gums and glucomannans effect the dietary fibers so that theyare softer in touch to the tongue. Although the amount of stabilizingagent used depends on the stabilizing property of a particular agent, itshould be at a ratio by weight of approximately 0.5 to 15, preferably,0.75 to 10 parts to 1 part of the foaming agent.

Usage of water should be 150 to 300, preferably about 180 to 250 partsby weight to 100 parts by weight in total of the soybean protein, starchand dietary fiber. If the water content is lower than 150 parts byweight, the dough is hard and insufficient in expandability, while thewater content of more than 300 parts by weight is unpreferable, becausethe dough comes to be sticky and poor in processability, and excessivepuffing may be caused, when it is processed by heat.

By mixing and kneading the raw materials, the puffed food doughaccording to the invention is obtained. Various additives conventionallyused in the food industry may be added to the dough according to adesired nutritional balance, form of food and the like. Such additivesmay be seeds, nuts, seaweed, leaves and the like. As seeds and nuts, forexample, sesame, macadamia nut, almond, hempseed, cashew nut, pumpkinseed, kaya seeds, gingko, chestnut, walnut, coconut, pistachio,hazelnut, pine nut, and peanut may be used. Specifically, sesame that isrich in vitamins and macadamia nut containing less cholesterol arepreferably employed. The seeds and nuts should be preferably added tothe dough after soaking in water and covering with soybean protein overa wet surface thereof for providing a higher adhesion to the dough, andpreventing them from falling from the puffed food when it is slicedafter puffing.

As seaweed, hijiki seaweed, kelp, wakame seaweed and the like may beused. Since seaweed are rich in minerals, by adding seaweed, thenutritional balance of the puffed food can be improved. In the case ofusing seaweed, it is preferable that raw seaweed is cut into anappropriate size, pieces subjected to a drying process at a lowtemperature such as freeze-drying after they have been blanched (i.e.soaked in hot water for a while), then, chipped or powdered before use.The blanching process is effective for vivifying and maintaining thecolor of seaweed, and reducing change in quality of the seaweed byinactivating thermally unstable enzymes in the seaweed.

For leaves, tea, carotenoid vegetables, Japanese mugwort and the likemay be employed. Such leaves contain various nutriments effective formaintenance of human health such as beta-carotene, flavonoids, andsuperoxide dismutase, and are effective for health maintenance. Althoughsuch leaves may be added to the dough without any processing, it ispreferable that they are subjected to such drying process at a lowtemperature as freeze-drying after blanching, and chipped or powderedsimilarly to the seaweed. When the leaves are added to the dough withoutany processing, they are preferably soaked in water, as described above,and added to the dough after they are covered with a soybean proteinover the wet surface thereof.

The above-mentioned various types of additives are respectively added atthe ratio of 15 parts or less, preferably, 5 to 10 parts by weight to100 parts by weight in total of a soybean protein, starch and dietaryfiber.

Furthermore, such conventional food additives used in the field may beappropriately added as seasonings as salt, sodium glutamate, sodiuminosinate, sodium guaninate, sugar, sweet oligo and oligosaccharidesyrup, acidifiers as citric acid and malic acid, thickening agent assodium alginate, vitamins as vitamins A, B, E and K and minerals ascalcium lactate, precipitated calcium carbonate, zinc gluconate, zincsulfate, copper gluconate and copper sulfate.

Although the dough may be prepared in various ways by appropriatelychanging the mixing sequence of the raw materials listed above, apreferred example of a preparation method is one where specified amountsof water and foaming agent are firstly placed in a mixer, a stabilizingagent is added thereto when it is required, then, the foaming andstabilizing agents are solved by agitation at a low speed using ahopper, and the mixture is sufficiently foamed by agitation at a highspeed (preferably, foamed approximately 8 to 10 times of water initiallyapplied). A specified amount of soybean protein, starch and dietaryfiber are added gradually to the foamed liquid, the additives andseasonings are applied, if desired, and the entirety is sufficientlyagitated. Then, by replacing the hopper with a hook, agitating themixture sufficiently, and forming it into a desired shape, the dough isobtained.

According to the method, the foaming performance of foaming agent ismaintained, and the dough with the materials mixed evenly can beobtained. It is preferable that solid materials contained in the doughshould be adjusted to approximately 25 to 50% by weight, if the contentof solid materials is less than 25%, the content of water in the doughis excessive, and the shape of dough cannot be maintained, while thepuffing is insufficient, if the content exceeds 50% by weight.

The dough obtained in such manner may be immediately processed by heatto make the puffed food, or frozen for storing it for a long time in astable condition. Such freezing and storing possibility is a maincharacteristic of puffed food dough according to the invention. In otherwords, as consumers become quality-oriented, and enjoy different stylesof meals, and a cold chain is developed, open fresh bakeries andbake-off shops are coming to be popular, where breads freshly baked fromfrozen dough there are sold. Although it is essential for such servicethat dough can be frozen and stored in a stable condition for a longtime, because conventional dough comprising wheat flour and yeast hassuch problems that 1. the dough comes to be bitter, because the yeastproduces an alcohol when it is frozen, and; 2. such freezing problem asinsufficient puffing is caused, because the yeast itself is destroyed,and aglutathione in the cell comes out, which breaks the S-S bond ofgluten, food products satisfactoin flavor and puffing cannot beobtained. Accordingly, a puffed food dough superior infreeze-storability is demanded, and the invention is effective forsolving such problem.

Incidentally, although the dough may be formed in a desired shape usingany conventional method, in the case of the dough that is frozen andstored, it is preferable to use an extruder or the like for shaping thedough under pressure. By shaping it under pressure, cracking in thedough surface can be prevented during freeze-storage. By preventingcracking of the dough, when the dough is heated, leakage of evaporatedwater is reduced, puffing is enhanced, and a puffed product having asuperior outlook can be obtained. In addition, for freezing and storingthe dough, it is preferable to quickly freeze the dough by using liquidnitrogen or the like.

The production method according to the invention comprising the step ofheating the dough obtained in such manner for puffing it to produce thepuffed food. In the operation, it is unnecessary to ferment the dough,and puffed food having an excellent flavor and touch can be obtained byheating either the dough immediately after it is obtained or the frozendough after or without thawing it.

Means for heating the dough is unspecified, and such conventionalheating method as heating by an oven and microwave irradiation may beemployed. Microwave heating is preferable. With microwave, heating, thedough is heated from the inside, resulting in a food higher in loafcapacity and evenly puffed. Moreover, when heating the dough by meansof, it is more preferable that the microwave heating be effected under aflow of air (preferably, at an air temperature of 70 ° to 110 ° C.) toprevent dewdrops being formed on a wall of the microwave irradiationchamber, and efficiently evaporating Water contained in the dough. Inaddition, by time-course change of microwave output to the dough,puffing can be controlled, and excessive heating and burning of thedough can be prevented.

The microwave heating is performed by irradiating microwaves to thedough, and microwaves with a frequency range of 13 MHz to 18,000 MHz aregenerally used, although it is not particularly specified. The energy ofthe microwaves used is also appropriately selected according to thewater content of the dough, irradiation time and the like. In microwave,heating it is preferred to provide air, i.e. under air flow, in order toprevent dewdrops from forming on a wall of the irradiation chamber byevaporated water, and assure efficient evaporation of the water. A flowrate of air should be appropriately selected according to the size ofdough being prepared, and an air temperature range of 70 ° to 110 ° C.is generally preferred in terms of efficiency, although it is notparticularly specified.

Microwave heating may be effected either by a batch or continuoussystem, or using a rotary-table system with a blower. It is alsopreferred that the dough be placed on a mesh or meshed belt comprisingmaterial that allows easy penetration of microwaves such asTeflon-coated glass fibers, reinforced plastics and the like, and themicrowaves are irradiated to the dough from both upper and lower sides.

Preferably, the microwave heating is conducted such that the microwaveoutput to the dough is sequentially changed for puffing the dough, andthe microwave radiation apparatus comprises plural chambers continuouslydisposed. Further that the microwave output is sequentially reduced froma high output in an initial irradiation chamber (first chamber) so thata large quantity of water is evaporated initially by feeding the doughcontinuously through the first chamber, and the output of microwaves isadjusted thereafter according to the puffing condition of the dough.

In more detail, in the case of a microwave radiation apparatuscomprising four chambers disposed continuously, it is preferable thatthe output of microwaves in the first and second chambers be changed inmultiple steps, such as 2.6 kW or 5.2 kW, and that in third and fourthchambers finely adjusted, for example, within a range of 0 to 5 kW, sothat the puffed food will be prevented from being burnt due to excessiveirradiation of microwaves. Thus puffed food products having differentpuffing degrees are easily produced, and forms of puffed food can bealso controlled by using such microwave radiation apparatus, andadjusting the outputs of the chambers.

In the case of producing the puffed food using an oven, the doughaccording to the invention can be heated by an oven in a conventionalmanner (at a temperature of 100 ° C. or higher, generally about 120 ° to250 ° C., preferably about 150 ° to 200 ° C. for 3 to 10 min, generally5 to 6 min) to produce the puffed food.

The puffed food product obtained according to the invention by suchheating methods as described above is similar to bread, cookie or chouof 2.5 to 5 times in puffing ratio, and can be used in such variousfields as bread, buns, snack food, pastry and food material. It isspecifically optimum as healthy food, because it is made of natural foodmaterials, and is reduced in cholesterol content. Moreover, it ischaracterized by a good flavor that is maintained for a long time. Thedough according to the invention can be also characterized in that it isfrozen for storage, and readily eaten, because such puffed food asdescribed can be obtained only by heating the frozen dough in storage.

EXAMPLE

The invention is described-in detail in the following Examples, itshould be understood that the invention is not limited by the Example.

Example 1

670 g of water and 4 g of Versa Whip K (tradename, a foaming agent ofsoybean protein) are put in a mixer, and slowly agitated dissolve thefoaming agent. Then, a solution containing 4 g of agar is added, andaggressively agitated to make about 8 to 10 times in volume of that ofthe water by foaming the mixture. While the foamed solution is agitated,210 g of Fuji Pro R (tradename, separated soybean protein), 120 g ofcorn starch and 20 g of polydextrose is gradually added, then, afteradding 2 g of salt and 10 g of sugar, the mixture is sufficientlyagitated. Succeedingly, after forming it by using an extruder, andcutting to about 120 g to 130 g a piece, a dough is obtained.

The dough obtained in such manner is placed on a meshed Teflon belt, andfed into a continuous microwave heating test apparatus (2450 MHz infrequency, 500W in output) so that it is subjected to microwaves fromupper and lower sides thereof for 3 min in a blowing condition of 110 °C. in temperature, and a puffed food similar to bread of about 3 timesin puffing ratio was obtained. The puffed food obtained had very finefoams evenly distributed therein, and was excellent in flavor and taste.

The dough obtained in such manner was also placed in a plastic bag,deaerated, sealed, then, quickly frozen by leaving it at -80 ° C. in acontact freezer for 5 min, and stored at -18 ° C. in a refrigerator, nocrack was found in a surface thereof. In addition, a puffed food wasobtained from the frozen dough by microwave heating in a mannerdescribed above. The puffed food obtained was similar in puffing ratioand flavor to one that was obtained by microwave-heating the doughimmediately after it was formed.

Examples 2 to 14

By using materials shown in Tables 1 and 2 below, a dough was obtainedby a method similar to that of Example 1, and subjected to microwaveheating to obtain a puffed food.

The dough obtained was similar to that of Example 1 infreeze-storability, and every puffed food obtained by heating processwas about 2.5 to 4 times in puffing ratio, and was excellent in finenessof-foams, flavor and taste similarly to those of Example 1.

                                      TABLE 1                                     __________________________________________________________________________    Embodiment No.                                                                          2      3       4       5        6      7      8                     __________________________________________________________________________    Water (ml)                                                                              670    650     650     650      650    650    650                   Foaming agent                                                                           Versa whip                                                                           Versa whip                                                                            Versa whip                                                                            Fuji Soft                                                                              Fuji Soft                                                                            Fuji Soft                                                                            Fuji Soft             (g)       K 4    K 4     K 4      4        4      4      4                    Stabilizing agent                                                                       Guar gum                                                                             Water-soluble                                                                         Soybean Glucomannans                                                                           Agar   Soybean                                                                              Psyllium              (g)        6     starch  protein  3        5     protein                                                                              seed gum                               10      40                      40      3                    Soybean protein                                                                         Fuji Pro R                                                                           Fuji Pro K                                                                            Fuji Pro V                                                                            Fuji Pro R                                                                             Fuji Pro R                                                                           Fuji Pro                                                                             Fuji Pro R            (g)       210    180     140     180      180    140    180                   Starch    Potato starch                                                                        Corn starch                                                                           Potato starch                                                                         Potato starch                                                                          Potato starch                                                                        Potato                                                                               Potato starch         (g)       100    60      90      60       100    100    120                   Dietary fiber                                                                           Bran   Powdered bean-                                                                        Powdered bean-                                                                        Bran     Corn fiber                                                                           Corn fiber                                                                           Polydextrose          (g)        30    curd refuse                                                                           curd refuse                                                                           60        40    40      20                                    30      60                                                   Additives (g)                    Mugwort powder                                                                         Green tea*                                                                           Hijiki                                                                               Sesame*                                                15        20    20      20                   Salt (g)   2      2       2                                                   Sugar (g)  10    10      10                                                   __________________________________________________________________________     *: Used after soaking in water, and covering with soybean protein.       

                                      TABLE 2                                     __________________________________________________________________________    Embodiment No.                                                                          9        10       11      12       13       14                      __________________________________________________________________________    Water (ml)                                                                              670      650      670     650      650      650                     Foaming agent                                                                           Fuji Soft                                                                              Fuji Soft                                                                              Fuji Soft                                                                             Fuji Soft                                                                              Celcream Celcream                (g)        4        4        4       4       11       18                      Stabilizing agent                                                                       Guar gum Guar gum Guar gum                                                                              Guar gum Guar gum Guar gum                (g)        6        6        6       6        6        6                      Soybean protein                                                                         Fuji Pro R                                                                             Fuji Pro R                                                                             Fuji Pro R                                                                            Fuji Pro R                                                                             Fuji Pro R                                                                             Fuji Pro R              (g)       180      180      180     180      200      210                     Starch    Potato starch                                                                          Potato starch                                                                          Potato starch                                                                         Potato starch                                                                          Waxy starch                                                                            Waxy starch             (g)       60       60       60      60       40       50                      Dietary fiber                                                                           Powdered bean-                                                                         Powdered bean-                                                                         Powdered bean-                                                                        Powdered bean-                                                                         Powdered bean-                                                                         Powdered bean-          (g)       curd refuse                                                                            curd refuse                                                                            curd refuse                                                                           curd refuse                                                                            curd refuse                                                                            curd refuse                       90       90       90      90       80       80                      Additives (g)                                                                           Mugwort powder                                                                         Green tea*                                                                             Hijiki powder                                                                         Sesame*                                             20       30       20      30                                        __________________________________________________________________________     *: Used after soaking in water, and covering with soybean protein.       

By analyzing the puffed food obtained in Example 13, it was found thatthe food contains, in 100 g thereof, 11.8 g of water, 50.2 g of protein,5.5 g of fat, 25.8 g of sugar, 2.3 g of fibers and 4.4. g of ash, andprovides 363 kcal of energy. Thus, it was recognized that the puffedfood obtained in such manner is rich in protein and dietary fibers, andcontains less fat.

Example 15

A dough obtained similarly to that of Example 1 was placed on a meshedplate in a form of thick drops of approximately 3 cm in diameter with aspacing between them, and heated in an oven at a temperature ofapproximately 200 ° C. for about 5. min, and a food material similar toa chou was obtained.

Example 16

A dough obtained in a manner similar to that of Example 1 was formedinto thin sheets, placed on a meshed plate with a spacing between them,and heated in a oven at a temperature of approximately 120 ° to 150 ° C.for about 5 min until the water content comes to be in the order of 25to 30%, and a non-fried food material similar to fried bean-curd wasobtained. The food material was seasoned according to a conventionalmethod, and a seasoned food material similar to fried bean-curd wasobtained.

INDUSTRIAL APPLICABILITY

According to the invention, a puffed food containing a soybean protein,starches and dietary fibers in a well-balanced manner, and significantlyreduced in cholesterol content, because the use of materials high incholesterol content such as eggs is avoided, can be obtained, and can beclaimed to be a healthy food. Moreover, the puffed food is superior inflavor and taste, excellent in puffing property and foaming evennesswithout using any egg-originated foaming agent.

Additionally, the dough according to the invention can be used forproducing the puffed food having such characteristics as describedabove, provides a good freeze-storability, because use of yeast, bakingpowders and the like are avoided, and is superior in controllability atthe time of freezing and storage.

We claim:
 1. A puffed food dough comprising soybean protein, starch anddietary fiber in a ratio by weight of from 1:0.2 to 0.8: 0.01 to 0.4,respectively, and from 0.5 to 5 parts by weight of a vegetable foamingagent and from 150 to 300 parts by weight of water per 100 parts byweight in total of the soybean protein, starch, and dietary fiber. Thedough does not contain a chemical leavening agent or yeast.
 2. Thepuffed food dough of claim 1, wherein the dough comprises soybeanprotein, starch and dietary fiber in a ratio by weight of from 1:0.33 to0.7:0.05 to 0.3, respectively.
 3. The puffed food dough of claim 1 or 2,wherein the vegetable foaming agent is an enzyme-decomposed soybeanprotein.
 4. The puffed food dough of claim 1, wherein the dough containsan additive selected from the group consisting of seeds, nuts, leavesand pieces of seaweed.
 5. The puffed food dough of claim 1, comprisingfrom 1 to 2 parts be weigh of the vegetable foaming agent and from 180to 250 parts by weight of the water per 100 parts by weight in total ofsoybean protein, starch and dietary fiber.
 6. A method for producing apuffed food product comprising preparing a dough containing soybeanprotein, starch and dietary fiber in a ratio by weight of from 1:0.2 to0.8:0.01 to 0.4, respectively, and from 0.5 to 5 parts by weight of avegetable foaming agent and from 150 to 300 parts by weight of water per100 parts by weight in total of the soybean protein, starch and dietaryfiber, said dough not containing a chemical leavening agent or yeast,and thereafter heating said dough to form said puffed food product. 7.The method of claim 6, wherein the dough contains soybean protein,starch and dietary fiber in a ratio by weight of from 1:0.33 to 0.7:0.05to 0.3, respectively.
 8. The method of claim 6 or 7, wherein thevegetable foaming agent is an enzyme-decomposed soybean protein.
 9. Themethod of claim 6, wherein the dough is heated in a microwaveirradiation apparatus or a heated oven.
 10. The method of claim 6,wherein the dough contains an additive selected from the groupconsisting of seeds, nuts, leaves and pieces of seaweed.